The effect of fertilization with the compost from forest humus and mulching with the fresh ectohumus on the soil properties, the growth of one-year old white birch seedlings as well as on the biological activity of soils in the forest nursery was investigated in the work. The biological activity was estimated with the use of bioindicatory method - mites (Acari), especially saprophage oribatid mites (Ori-batida) were used as biological indices.
The pedosphere of studied area in the forest nursery had acid reaction (pH), and the mulching with the fresh forest ectohumus decreased additionally this value. On the basis of analysis of available P and K, it was found that there was small differentiation between plots fertilized with mineral fertilization and those fertilized with the compost and mulched with the fresh ectohumus. Fertilization with the compost significantly increased the height and the fresh mass of the above-ground parts of one-year old white birch seedlings. Influence of mulching - conducted in September - on these parameters was not detected. In the spring sea-son, before the mulching measure, the density of mites was low. After the mulching measure, the number of mites - especially saprophage oribatid mites - was dis-tinctly increased. On the mulched plots there were 15-16 taxa of Oribatida, and Tectocepheus velatus was dominant in their gatherings.